NEW YORK -- Former Ukrainian Prime Minister Yulia Tymoshenko has filed a lawsuit in a U.S. court in New York City on behalf of Ukrainians.

The lawsuit accuses gas trader RosUkrEnergo and the businessman Dmitry Firtash of a conspiracy to rob Ukraine of natural gas supplies.

Tymoshenko disputes the ruling of the Stockholm Arbitration Court from last year, which determined that the state energy company NAK Naftogaz Ukrainy owed RosUkrEnergo and Firtash 12.1 billion cubic meters of gas.

The gas had already been paid by the government, Tymoshenko claims.

Under U.S. law, foreigners can seek justice there if they believe their rights under international conventions have been violated.

Tymoshenko's lawsuit, filed April 26, seeks to represent all Ukrainian people in a class-action suit, and seeks unspecified damages.